Evidence for differences in the thermal histories of Antarctic and non-Antarctic H chondrites with cosmic-ray expsoure ages < 20 Ma

Journal Article · Mon Apr 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90178-8· OSTI ID:5599957

Sears, D W.G.; Benott, P; Batchelor, J D ^[1]

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1. Univ. of Arkansas, Fayetteville (USA)

Antarctic H chondrites show a different range of induced thermoluminescence properties compared with those of H chondrites that have fallen elsewhere in the world. Recent noble gas data show that this difference is displayed most dramatically by meteorites with cosmic-ray exposure ages less than 20 Ma, and they confirm that the differences cannot be attributed to weathering or to the presence of a great many fragments of an unusual Antarctic meteorite. Annealing experiments on an H5 chondrite, and other measurements on a variety of ordinary chondrites, have shown that induced TL properties are sensitive to the thermal histories of the meteorites. The authors conclude that the event(s) that released the less than 20 Ma samples, which are predominantly those with exposure ages of 8{plus minus}2 Ma, produced two groups with different thermal histories, one that came to earth several 10{sup 5} years ago and that are currently only found in Antarctica, and one that is currently falling on the earth.

• OSTI ID: 5599957
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 55:4; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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